virtualbox.org

I'm trying to install Ubuntu 9.10 64-bit guest on a Ubuntu 9.10 64-bit host.
Virtualbox 3.0.10 installed OK.
VM created.

But when I start the VM, vbox says:

Failed to start the virtual machine Ubuntu Server 9.10.
VT-x is not available. (VERR_VMX_NO_VMX).
Unknown error creating VM (VERR_VMX_NO_VMX).

Details
Result Code: NS_ERROR_FAILURE (0x80004005)
Component: Console
Interface: IConsole {0a51994b-cbc6-4686-94eb-d4e4023280e2}

I definitely have Intel VT enabled in the BIOS (American Megatrends v2.6 R01-A3).
Processor: Intel Core 2 Duo E6850 3.0GHz
RAM: 4GB

Has anyone been able to successfully run Ubuntu 9.10 64-bit guest on a 64-bit Ubuntu host? What am I missing here?

Look for hardware virtualization in the bios. That is what you need not just 64 bit.